People are creative and maybe someone got a solution, but I wouldn't bet on it. In order to stream audio you need a piece of software that can interpret the digital data (a codec) and a communication layer that implements a streaming protocol. Finally, one should tamper with the BT device so that it advertises itself as an audio device.
So I have no suggestion, but you may look at the wikipedia page on BT profiles, especially the Advanced audio distribution profile, here List of Bluetooth profiles - Wikipedia, to get a clearer picture of what is involved.
[edit] After writing this I got curious and googled for A2DP arduino. Here's something that may be of interest: Bluetooth Breakout - Bluegiga WT-32 - WRL-08952 - SparkFun Electronics.